Help with Grignard Reactions: I'm Stuck!

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SUMMARY

The discussion focuses on Grignard reactions, specifically the nucleophilic addition of Grignard reagents to carbonyl compounds. The key steps involve the formation of a tetrahedral intermediate, stabilized by a magnesium halide cation, followed by an acid work-up that yields a secondary alcohol when starting with an aldehyde. Participants emphasize the importance of understanding the mechanism rather than memorizing reactions, advocating for a step-by-step approach that includes drawing electron-pushing diagrams and identifying intermediates.

PREREQUISITES
  • Understanding of Grignard reagents and their properties
  • Knowledge of carbonyl chemistry, specifically aldehydes and ketones
  • Familiarity with nucleophilic addition mechanisms
  • Basic skills in drawing reaction mechanisms and electron-pushing diagrams
NEXT STEPS
  • Study the mechanism of Grignard reactions in detail
  • Learn about the formation and stabilization of tetrahedral intermediates
  • Explore acid work-up procedures in organic synthesis
  • Investigate common mistakes in organic chemistry to avoid memorization
USEFUL FOR

Chemistry students, organic chemists, and anyone involved in synthetic organic chemistry who seeks to deepen their understanding of Grignard reactions and their mechanisms.

ahazen
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I need help with the reaction.

I know the double bond O goes to single bond O-H

I'm not sure what else to do.

Thanks
 

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You're doing O. Chem wrong. Don't *memorize* the net result of a transformation, or you'll just memorize thousands and thousands of reactions. It's like physics: don't memorize the net equation of all the forces acting on a body for every situation, know how to derive them!

Approach this problem step by step, draw the electron-pushing and the intermediates/transition states, or you will be hopelessly lost.

Grignard Reagents are effectively "R-" or nucleophilic alkyl chains. You have an electrophilic carbon here (i.e., carbonyl C), so the first stop is going to be a nucleophilic addition to the carbonyl to form a tetrahedral intermediate, stabilized by MgX cation. Acid work-up will produce a secondary alcohol (since you're starting with an aldehyde).
 

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